Abstract

                                Field investigation was carried out at Agricultural College and Research Institute, Madurai during summer 2006 and winter 2006-2007 to elicit information on the effect of intercropping system, inorganic fertilizers, biofertilizers and leaf extract spray on microbial population of cotton rhizosphere and seed cotton yield. The experiments were laid out in a split plot design with three replications. Intercropping system viz., C1 – Cotton sole, C2 – Cotton + Blackgram, C3 – Cotton + Greengram and C4 – Cotton + Cluster bean were allotted to mainplot. The intercrops residues were incorporated at 65 DAS. The subplot consisted of six nutrient management and botanicals spray treatments viz., N1 - 100 % RDF (Recommended Dose of fertilizer – 80:40:40 kg NPK/ha), N2 – 75 % RDF, N3 - 75 % RDF + biofertilizers, N4 -75 % RDF + 5 % Morinda leaf extract spray at 60 and 80 DAS, N5 - 75 % RDF + 5 % Vilvam leaf extract spray at 60 and 80 DAS, N6 - 75 % RDF + 5 % Annona leaf extract spray at 60 and 80 DAS. The biofertilizers include azospirillum + Phosphobacteria + silicate solubilizing bacteria each at 2.6 kg/ha. The results revealed that cotton + blackgram intercropping has produced higher microbial count with more seed cotton yield. Among the nutrient management treatments application of 75 % RDF + combined application of azospirillum, phosphobacteria and silica solubilizing bacteria recorded higher microbial population and seed cotton yield.

Key words : Intercropping, nutrient management, biofertilizers, leaf extract spray